The use of BIs for verifying the effectiveness of a sterilization or decontamination cycle or process in health care, pharmaceutical, food processing and related fields is well known. Typically, these BIs include a known calibrated population of bacterial spores that are highly resistant to the sterilization process and are inoculated onto a carrier. The composition and use of such BIs have previously been described in my U.S. Pat. No. 5,856,118. This patent discloses a BI including a plurality of carriers inoculated with bacterial spores individually compartmentalized in a package. This patent is incorporated herein by reference in its entirety.
The BIs described in U.S. Pat. No. 5,856,118 include a sealed package that is permeable to gaseous vapors including hydrogen peroxide, yet provides a microbial barrier to an external environment. These “sealed” BIs are placed in a sterilization chamber and exposed to the sterilization process, the carrier inoculated with the bacterial spore remaining sealed within the package. The sealed package is opened after the sterilization process so that the carriers with the spores can be placed in a culture medium to test for survival of any of the inoculated spores on the carriers. Care must be taken when removing the inoculated carriers to ensure that microbial contaminants are not introduced to the culture medium. These contaminants could result in a “false positive” result if bacterial growth is observed in the culture medium implying that the sterilization process was ineffective.
Another type of BI includes an unpackaged inoculated carrier which is called “bare” BI. This type of BI also includes a carrier inoculated with spores, but is not contained within any individually sealed package during exposure to the sterilization cycle. These BIs may be placed within tubing or other restricted spaces prior to exposure to the sterilization cycle. Bare BIs having carriers in strip form are available from Apex, a Division of Mesa Laboratories of Bozeman, Mont. and are provided in a protective package. These strip BIs are not individually sealed. Rather, the strip BI is removed from a protective sleeve and placed in a chamber for the sterilization process. The strip BI is not influenced by a package during the sterilization process. However, with this type of BI, there is a possibility for microbial contamination due to handling in an environment outside of the sterilization chamber. This contamination may be both from spores escaping into the environment from the BI, or contamination of the BI with external microbes leading to false positive test results during culturing.
The above-referenced BIs have been found quite useful in determining the effectiveness of sterilization cycles. However, these BIs can be improved upon by providing BIs having an integral package as described in the present invention.